The objective of this Project is to examine different prevent modalities for their ability to suppress and/or eliminate periodontal pathogens, particularly B. forsythus, P. gingivalis and T. denticola (red complex), in periodontally healthy subjects and periodontitis subjects enrolled in a maintenance program. Subjects will be recruited at 2 geographic locations, Forsyth Cental Center and the University of Gothenburg, Sweden each site providing 50% of the subjects for each Aim. In Specific Aim 1, 160 periodontally healthy subjects harboring all members of the red complex, as determined by PCR, will be assessed clinically at 6 periodontal sites per tooth at baseline. Plaque samples will be taken from the mesial aspect of each tooth and evaluated individually for their content of 40 bacterial species using checkboard DNA-DNA hybridization. Subjects will be randomly assigned to test or control groups. Test subjects will perform home are procedures using a powered toothbrush and a triclosan containing dentifrice, while control subjects will use a manual brush and a control dentifrice for the 3 years of the study. Clinical and microbiological assessments will be repeated at 1,2 and 3 years. SA2 is similar to SA1 except that the population will consist of 120 adult periodontitis subjects who he completed periodontal therapy and are enrolled in a maintenance program. The prevention regimens will be more comprehensive since these subjects will have residual pockets, altered gingival architecture and higher levels of periodontal pathogens. After baseline monitoring, subjects will be randomly assigned to test and control groups. Controls will receive the preventive protocol outlined for SA1. Test subjects will perform supragingival plaque removal as descried for SA1 for 3 years but will also perform interdental cleaning, tongue brushing and rinsing with chlorhexidine. Half of the subjects in both test and control groups will receive Actisite at pockets >4 mm for 10 days after the baseline examination providing a 2 x 2 factorial design. Monitoring will be repeated at 3 months, 1.2 and 3 years. New and improved prevention agents/devices are constantly being developed. Thus, in SA3, 3 new prevention modalities will be evaluated in 160 periodontitis subjects as described for SA2 for 6 months. The results of this Project should help define optimum strategies for the prevention of periodontal diseases in healthy subjects and for prevention of disease recurrence in treated periodontitis subjects.